Temporary suppression of tinnitus by modulated sounds

Despite high prevalence of tinnitus and its impact on quality life, there is no cure for tinnitus at present. Here, we report an effective means to temporarily suppress tinnitus by amplitude- and frequency-modulated tones. We systematically explored the interaction between subjective tinnitus and 17 external sounds in 20 chronic tinnitus sufferers. The external sounds included traditionally used unmodulated stimuli such as pure tones and white noise and dynamically modulated stimuli known to produce sustained neural synchrony in the central auditory pathway. All external sounds were presented in a random order to all subjects and at a loudness level that was just below tinnitus loudness. We found some tinnitus suppression in terms of reduced loudness by at least one of the 17 stimuli in 90% of the subjects, with the greatest suppression by amplitude-modulated tones with carrier frequencies near the tinnitus pitch for tinnitus sufferers with relatively normal loudness growth. Our results suggest that, in addition to a traditional masking approach using unmodulated pure tones and white noise, modulated sounds should be used for tinnitus suppression because they may be more effective in reducing hyperactive neural activities associated with tinnitus. The long-term effects of the modulated sounds on tinnitus and the underlying mechanisms remain to be investigated.